This invention relates generally to a business form with removable label, as improved process for producing the same, and an improved transfer adhesive stock for producing a removable label.
The use of business forms having removable labels has become commonplace in not only industry but the lives of nearly everyone. A business will often imprint information which then can be transferred to a document by the use of a label. For example, a label may be pre-printed with a name and address that can be used in sending return correspondence. Similarly, the label can request certain information. The requested information can be written on the label and the label then placed on an envelope or other such document.
These labels are commonly referred to as "integrated labels". Generally, they are comprised of two layers of materials. The first or lower layer has a pressure sensitive adhesive on its bottom surface and an adhesive on its upper surface which detachably secures a second layer, a paper label, thereto. Another version of an integrated label has a lower layer with pressure sensitive adhesive on its upper surface which detachably secures the paper label thereto, no adhesive is applied to the bottom surface of the lower layer.
In addition, there are different methods of producing such labels. One may refer to U.S. Pat. No. 4,379,573, issued Apr. 12, 1983 and U.S. Pat. No. 5,324,153, issued Jun. 28, 1994, for a general discussion thereof. Prior labels generally were produced with self-wound transfer tape. This consisted of a single release liner ply with adhesive. This liner ply was coated with a silicone release material on the top and bottom surfaces of the liner ply. There was a difference in adhesive affinity between the top and bottom surfaces. A pressure sensitive adhesive then was applied to one side of the liner. The liner with adhesive was wound upon itself (hence the term "self-wound"). Because of the difference in adhesive affinity on each side of the liner, when the liner was unwound, the adhesive stays firmly in contact with the side of the liner with the "tighter" release.
However, this self-wound transfer tape has several problems. The first problem is that the conventional transfer tape has a relatively low moisture content because of two exposures to heat for curing the silicone on each side of the tape. When wider transfer tapes (required for many integral labels) are applied there is a moisture content imbalance between the form and the tape. As the liner reaches equilibrium, it expands (especially across the grain). This results in wrinkles or buckles in the transfer tape atop the form. A second problem is that self-wound transfer tapes are relatively thick, approximately 3 mils. Another problem is the fact that since the tape is silicone coated on both sides, the forms when stacked have a tendency to slide around and not stay neatly stacked. In addition, the silicone coated side will not accept printing thereon. A further problem with using conventional self-wound transfer tape is that the rollers which guide the transfer tape during the "unwinding" process must be treated with special silicone laminate so that the tape does not stick to the rollers.